js判断浏览器的环境（pc端，移动端，还是微信浏览器）

 // 判断浏览器函数
 function isMobile(){
  if(window.navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i)) {
   return true; // 移动端
  }else{
   return false; // PC端
  }
 }

var os = function() { 
  var ua = navigator.userAgent, 
  isWindowsPhone = /(?:Windows Phone)/.test(ua), 
  isSymbian = /(?:SymbianOS)/.test(ua) || isWindowsPhone, 
  isAndroid = /(?:Android)/.test(ua), 
  isFireFox = /(?:Firefox)/.test(ua), 
  isChrome = /(?:Chrome|CriOS)/.test(ua), 
  isTablet = /(?:iPad|PlayBook)/.test(ua) || (isAndroid && !/(?:Mobile)/.test(ua)) || (isFireFox && /(?:Tablet)/.test(ua)), 
  isPhone = /(?:iPhone)/.test(ua) && !isTablet, 
  isPc = !isPhone && !isAndroid && !isSymbian; 
  return { 
   isTablet: isTablet, 
   isPhone: isPhone, 
   isAndroid : isAndroid, 
   isPc : isPc 
  }; 
}(); 
 
// 使用方法 
if(os.isAndroid || os.isPhone){
alert("-----");
}

window.isInWeixinApp = function() {
    return /MicroMessenger/.test(navigator.userAgent);
  };

/**
   * 判断是否是微信环境
   */
  function getIsWxClient () {
    var ua = navigator.userAgent.toLowerCase();
    if (ua.match(/MicroMessenger/i) == "micromessenger") {
      return true;
    }
    return false;
  };

 var isWechart = function () {
  var rst = true
  if(window.navigator.userAgent.match(/(phone|pad|pod|iPhone|iPod|ios|iPad|Android|Mobile|BlackBerry|IEMobile|MQQBrowser|JUC|Fennec|wOSBrowser|BrowserNG|WebOS|Symbian|Windows Phone)/i)){
   var ua = navigator.userAgent.toLowerCase();
   if (!(ua.match(/MicroMessenger/i) == "micromessenger")) {
    rst = false;
   }
  }else {
   rst = false;
  }
  return rst;
 }

 //平台、设备和操作系统 
   var system = { 
    win: false, 
    mac: false, 
    xll: false, 
    ipad: false 
   }; 
   //检测平台 
   var p = navigator.platform; 
   system.win = p.indexOf("Win") == 0; 
   system.mac = p.indexOf("Mac") == 0; 
   system.x11 = (p == "X11") || (p.indexOf("Linux") == 0); 
   system.ipad = (navigator.userAgent.match(/iPad/i) != null) ? true : false; 
   //跳转语句，如果是手机访问就自动跳转到wap.baidu.com页面 
   if (system.win || system.mac || system.xll || system.ipad) { 
    alert("在PC端上打开的");
   } else { 
    var ua = navigator.userAgent.toLowerCase(); 
    if(ua.match(/MicroMessenger/i)=="micromessenger") { 
     alert("在手机端微信上打开的"); 
    } else { 
     alert("在手机上非微信上打开的"); 
    } 
   }

/**
   *判断是否是app环境
   */
  function getIsApp () {
    var ua = navigator.userAgent.toLowerCase();
    if (ua.match(/isapp/i) == "isapp") {
      return true;
    }
    return false;
  };

/**
   *判断是否是app环境
   */
  function getIsApp () {
    var ua = navigator.userAgent.toLowerCase();
    if (ua.match(/isapp/i) == "isapp") {
      return true;
    }
    return false;
  };

function isIPhoneX(fn){
  var u = navigator.userAgent;
  var isIOS = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/); //ios终端
  if (isIOS) {    
    if (screen.height == 812 && screen.width == 375){
      //是iphoneX
    }else{
      //不是iphoneX
    } 
  }
}